/Engine/Plugins/Experimental/Water/Source/Runtime/Public/WaterQuadTree.h
Bilinear interpolation between four neighboring base height samples around InWorldLocationXY. The samples are done on the leaf node grid resolution. Returns true if all 4 samples were taken in valid nodes
bool QueryInterpolatedTileBaseHeightAtLocation ( const FVector2D & InWorldLocationXY, float & OutHeight ) const